A. Field of the Invention
The present invention relates to the separation or isolation of the outer covering or pericarp tissue from the remainder of a seed.
B. Problems in the Art
A variety of circumstances requires the removal of the outer coating or pericarp of a seed. Most times, it is not a trivial task. The pericarp is usually a layer, several cells thick. Tissues or other adhering structure(s) connect the pericarp to the interior part of the seed. This, coupled with the relatively small size of most seeds, makes separation and removal of pericarp difficult, or at least time consuming and laborious.
Corn pericarp is an example. It is the mature ovarian female tissue of the seed. It protects the interior endosperm and embryo from disease and moisture loss. However, it has a special make-up; analogous to a fingernail. Tissues of the underlying endosperm adhere to the pericarp. Separation of the pericarp is not simply a matter of sorting.
Some of the reasons separation of pericarp from the remainder of the seed is desirable are as follows.
It is desirable to separate and discard corn pericarp from its endosperm in some food processing applications. The make up of pericarp detrimentally affects the nature and composition of the end product.
Pericarp removal is important as a preparatory step to perform biological tests to identify the genetic origin of corn germplasm. However, instead of removing it to discard it, in these instances it is desirable to isolate and retain the pericarp, but it should be free of any other seed tissue derived from the male and female, to obtain pure female DNA.
Still further, separation and isolation of corn pericarp is desirable in some cases to extract substances from the pericarp, for example, specific nucleic acids, proteins, vitamins, and other dietary or nutraceutical compounds. The pericarp can be rich in such substances.
Because of such needs, pericarp removal processes have been developed and used in the art. A conventional pericarp removal method in food processing applications involves soaking corn kernels in a chemical solution (e.g. sodium hydroxide (NaOH) and/or hydrogen peroxide (H2O2)) for a relatively long period of time (e.g. hours). Such chemical soaking has been found to substantially loosen pericarp such that an automated method of separation can be used to separate the loosened pericarp from the endosperm. These methods allow batches of a substantial number of kernels to be processed, and the process to be automated. However, such processes take a significant amount of time (e.g. hours of soaking) to get the pericarp sufficiently loosened. They also require the chemicals, and the costs and handling associated therewith. Additionally, the chemicals used tend to damage or otherwise effect the DNA in the pericarp.
Therefore, because damage to DNA must be avoided, when separating pericarp from the remainder of the kernel for genetic analysis, current conventional methodologies have stayed away from the chemical steeping. Instead, current methods involve trying to somewhat loosen the pericarp by soaking the kernels overnight in distilled water instead of chemicals. After such soaking, seed by seed, the pericarp is manually cut or picked off. Water soaking is not as effective as chemical baths at loosening the pericarp. Although a relatively small number of seeds is needed for each batch to obtain enough pericarp material for genetic analysis (usually on the order of 10 to 100 or so), such seed-by-seed manual removal, with this number of seeds, can take one, two, or more person-hours. Furthermore, it is difficult, if not impossible, to completely remove all endosperm from the pericarp with these manual methods, contrary to the purity level needed or desired for accurate genetic testing results.
Therefore, there is a need for an improvement in the art relative to pericarp removal. A primary object, feature, or advantage of the present invention is the provision of a method and apparatus, which improves over the state of the art. Further objects, features and advantages of the present invention include an apparatus or method that:                1. allows effective pericarp removal, which is less labor intensive and time-consuming;        2. has applicability to either single or small amounts of seeds, or to relatively large numbers of seeds;        3. is adaptable to bulk processing;        4. is adaptable to high purity pericarp isolation from the remainder of the seed;        5. is adaptable to pericarp removal for a variety of applications, including but not limited to food processing and extraction of pericarp for analysis or extraction substances;        6. is scalable in volume while retaining time and labor efficiencies;        7. is adaptable to substantial or even total automation.        
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.